[Python-Dev] Type hints -- a mediocre programmer's reaction (original) (raw)

Robert Collins robertc at robertcollins.net
Tue Apr 21 22🔞43 CEST 2015

On 22 April 2015 at 04:28, Guido van Rossum <guido at python.org> wrote:

On Tue, Apr 21, 2015 at 12:49 AM, Antoine Pitrou <solipsis at pitrou.net> wrote:

On Mon, 20 Apr 2015 20:43:38 -0400 "R. David Murray" <rdmurray at bitdance.com> wrote: > +1 to this from me too. I'm afraid that means I'm -1 on the PEP. > > I didn't write this in my earlier email because I wasn't sure about it, > but my gut reaction after reading Harry's email was "if type annotations > are used in the stdlib, I'll probably stop contributing". That doesn't > mean that's true, but that's the first time I've ever had that > thought, so it is probably worth sharing. I think it would be nice to know what the PEP means for daily stdlib development. If patches have to carry typing information each time they add/enhance an API that's an addition burden. If typing is done separately by interested people then it sounds like it wouldn't have much of an impact on everyone else's workflow. This point will be moot until new code appears in the stdlib whose author likes type hints. As I said, we won't be converting existing code to add type hints (I'm actively against that for the stdlib, for reasons I've explained already). If type hints prove useful, I expect that adding type hints **to code that deserves them** is treated no different in the workflow than adding tests or docs. I.e. something that is the right thing to do because it has obvious benefits for users and/or future maintainers. If at some point running a type checker over the stdlib as part of continuous integration become routine, type hints can also replace certain silly tests. Until some point in a possible but distant future when we're all thinking back fondly about the argument we're currently having, it will be the choice of the author of new (and only new) stdlib modules whether and how to use type hints. Such a hypothetical author would also be reviewing updates to "their" module and point out lack of type hints just like you might point out an incomplete docstring, an outdated comment, or a missing test. (The type checker would be responsible for pointing out bugs. :-P )

What about major changes to existing modules? I have a backlog of intended feature uplifts from testtools into unittest - if the type hints thing works out I am likely to put them into testtools. Whats your view on type hints to such new code in existing modules?

-Rob

-- Robert Collins <rbtcollins at hp.com> Distinguished Technologist HP Converged Cloud

More information about the Python-Dev mailing list